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631.
632.
Marcos Melo Silva Anand Subramanian Thibaut Vidal Luiz Satoru Ochi 《European Journal of Operational Research》2012
The Minimum Latency Problem (MLP) is a variant of the Traveling Salesman Problem which aims to minimize the sum of arrival times at vertices. The problem arises in a number of practical applications such as logistics for relief supply, scheduling and data retrieval in computer networks. This paper introduces a simple metaheuristic for the MLP, based on a greedy randomized approach for solution construction and iterated variable neighborhood descent with random neighborhood ordering for solution improvement. Extensive computational experiments on nine sets of benchmark instances involving up to 1000 customers demonstrate the good performance of the method, which yields solutions of higher quality in less computational time when compared to the current best approaches from the literature. Optimal solutions, known for problems with up to 50 customers, are also systematically obtained in a fraction of seconds. 相似文献
633.
Luciana S. A. de Melo Anderson S. L. Gomes Sybele Saska Karina Nigoghossian Younes Messaddeq Sidney J. L. Ribeiro Renato E. de Araujo 《Journal of fluorescence》2012,22(6):1633-1638
We demonstrate the potential application of silver-pectin nanoparticles on photodynamic therapy, on a solution-base platform. Photodynamic therapy is a medical technique which uses a combination of photosensitizing drugs and light to induce selective damage on the target tissue, by electronically excited and highly reactive singlet state of oxygen. Metal enhanced singlet oxygen generation in riboflavin water solution with silver-pectin nanoparticles was observed and quantified. Here 13 nm silver nanospheres enclosed by a pectin layer were synthesized and it interaction with riboflavin molecule was analyzed. Pectin, a complex carbohydrate found in plants primary cell walls, was used to increase the biocompatibility of the silver nanoparticles and to improve metal enhanced singlet oxygen generation (28.5 %) and metal-enhanced fluorescence (30.7 %) processes at room temperature. The singlet oxygen sensor fluorescent green reagent was used to quantify the enhancement of the riboflavin singlet oxygen production induced by the silver colloid. We report a 1.7-fold increase of riboflavin emission and a 1.8-fold enhancement of singlet oxygen production. 相似文献
634.
Sand-moving winds blowing from a constant direction in an area of high sand availability form transverse dunes, which have a fixed profile in the direction orthogonal to the wind. Here we show, by means of a linear stability analysis, that transverse dunes are intrinsically unstable. Any perturbation in the cross-wind profile of a transverse dune amplifies in the course of dune migration due to the combined effect of two main factors, namely: the lateral transport through avalanches along the dune’s slip-face, and the scaling of dune migration velocity with the inverse of the dune height. Our calculations provide a quantitative explanation for recent observations from experiments and numerical simulations, which showed that transverse dunes moving on the bedrock (or “transverse sand ridges”) cannot exist in a stable form and decay into a chain of crescent-shaped barchans. 相似文献
635.
Carles A. C. Macieira Suely J. P. Correia Ana Paula Belizário de Sousa Ricardo L. C. Albuquerque Júnior Yzila L. F. Maia Araújo Mateus S. Melo Luiz P. Costa Juliana C. Cardoso Francine F. Padilha 《Macromolecular Symposia》2010,296(1):609-616
The use of casein, starch and bee pollen as biodegradable materials has been promise. The objective of this work was the development and characterization of films containing casein, pollen and starch. The films were obtained by casting process and the solvent evaporation was performed at 40 °C/24 h. The films characterization was carried out by microscopy, thermal analysis, opacity test, mechanical properties and barrier methods. The starch films presented heterogeneous on microscopy analysis. The thermal behaviors of pollen films were similar. The formulation containing only pollen 3% was unable to form film. The introduction of pollen in starch film formulation improved the mechanical characteristic and thermal stability of films. 相似文献
636.
A. M. Garrido Pedrosa D. M. A. Melo M. J. B. Souza A. S. Araujo S. H. Lima M. A. F. Melo J. M. Sasaki 《Journal of chemical crystallography》2009,39(3):186-192
Abstract Catalysts of Pt/WO
x
–ZrO2 type with 1 wt% of Pt and 10, 15 and 20 wt% of tungsten were synthesized and characterized. The structural and morphological
features of these catalysts were studied. The samples were synthesized by impregnation method and calcined at 600 °C, 700 °C
and 800 °C. The characterizations were carried out using different techniques: X-ray diffraction, Raman spectroscopy, scanning
electronic microscopy, nitrogen adsorption measurement and refinement of their crystalline structures by Rietveld method.
X-ray diffraction patterns revealed the formation ZrO2 and WO3 crystalline structures and its crystallite size were determined. The zirconium oxide crystallized into tetragonal and monoclinic
phases and tungsten trioxide crystallized into monoclinic phase. Crystalline WO3 and amorphous WO
x
species were detected by Raman spectra.
Index Abstract Catalysts of Pt/WO
x
–ZrO2 type with 1 wt% of Pt and 10, 15 and 20 wt% of tungsten were synthesized and characterized. The structural and morphological
features of these catalysts were studied. The samples were synthesized by impregnation method and calcined at 600 °C, 700 °C
and 800 °C. The characterizations were carried out using different techniques: X-ray diffraction, Raman spectroscopy, scanning
electronic microscopy, nitrogen adsorption measurement and refinement of their crystalline structures by Rietveld method.
X-ray diffraction patterns revealed the formation ZrO2 and WO3 crystalline structures and its crystalline size were determined. The zirconium oxide crystallized into tetragonal and monoclinic
phases and tungsten trioxide crystallized into monoclinic phase. Crystalline WO3 and amorphous WO
x
species were detected by Raman spectra. 相似文献
637.
Regina S. Burachik Alfredo N. Iusem Jefferson G. Melo 《Journal of Global Optimization》2010,46(3):347-361
We apply a modified subgradient algorithm (MSG) for solving the dual of a nonlinear and nonconvex optimization problem. The
dual scheme we consider uses the sharp augmented Lagrangian. A desirable feature of this method is primal convergence, which means that every accumulation point of a primal sequence (which is automatically generated during the process), is
a primal solution. This feature is not true in general for available variants of MSG. We propose here two new variants of
MSG which enjoy both primal and dual convergence, as long as the dual optimal set is nonempty. These variants have a very
simple choice for the stepsizes. Moreover, we also establish primal convergence when the dual optimal set is empty. Finally,
our second variant of MSG converges in a finite number of steps. 相似文献
638.
639.
D. M. de-Paula M. A. S. Melo J. P. M. Lima M. Nobre-dos-Santos I. C. J. Zanin L. K. A. Rodrigues 《Laser Physics》2010,20(6):1475-1480
Abstract
Photo-disinfection of deep dentin caries lesions may be a useful tool for preserving tooth structure. However, increase of pulpal temperature higher than 5.5°C may put pulp vitality in danger. 相似文献640.
D. M. A Melo G. Vicentini L. B. Zinner K. Zinner H. K. S. de Souza M. K. S Batista A. M. Garrido Pedrosa R. F. Bezerra 《Journal of Thermal Analysis and Calorimetry》2004,75(2):623-628
Complexes of neodymium and europium with amides and aminoxides were synthesized and characterized by complexometric analyses
with EDTA, CHN microanalytical procedures, IR absorption spectra, absorption spectra of neodymium complexes, emission spectrum
of europium compounds at 77 K, thermogravimetric analyses in N2 and differential scanning calorimetry (DSC) in N2. Infrared
spectroscopy results revealed that the nitrate molecules are bound to the central ions as bidentate. Thermogravimetric plots
indicated that the decomposition of the complexes occurs in the range 363-1163 K and resulted in the formation of Ln2O3 residues.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献